1. Field of the Invention
The present invention relates to an ink jet printer having an ink jet recording head and an ink cartridge for supplying ink to the ink jet recording head. More particularly, the present invention relates to an ink jet printer wherein, among the ink jet recording head and ink cartridge, at least the ink cartridge is exchangeable, and to a recording head removable with respect to the ink jet printer for exchange, and further to an ink cartridge (refer to also as "ink cassette" hereinafter) removable with respect to the recording head. Further, the present invention relates to an ink jet recording unit for sale, having a specific construction.
2. Related Background Art
Recently, in order to record information on a recording medium such as a paper, various techniques have been proposed. Among them, there is an ink jet recording system. In the ink jet recording system, ink is supplied to a recording head from an ink cartridge accommodating the ink therein, and then the ink is discharged from ink drop jet nozzles formed in the recording head on the recording medium (such as a paper) as ink drops created by means of electrical-mechanical converting elements or more preferably electrical-thermal converting elements, thereby recording an image on the recording head. Accordingly, the ink jet recording system has advantages that (a) a sharp image can be recorded on a recording paper regardless of the roughness of the surface of the recording paper, since the recording head does not directly contact the recording paper, and (b) not only a monocolor image but also a full color image can be obtained, since the image information is recorded as the combination of (ink) dots.
In such an ink jet recording system, various ink supplying methods have been proposed. Particularly, an ink supplying method using an exchangeable ink cartridge has a meritorious advantage that the running cost of the recording operation can be considerably reduced by using the ink cartridge having large capacity.
In the ink jet printer using the exchangeable ink cartridge, when the ink in one ink cartridge is used up, by replacing the empty cartridge by a new spare ink cartridge, the expensive recording head can be used for a long time regardless of the capacity or volume of the ink cartridge, with the result that the running cost can be reduced.
The structure for mounting and dismounting the ink cartridge with respect to the recording head is disclosed, for example, in the U.S. Pat. No. 4,306,245. Further, the U.S. Pat. No. 4,771,295 discloses an ink jet printer wherein an ink accommodating portion is formed integrally with a recording head portion and, when ink in the ink accommodating portion is used up (which can be detected by imperfect or erroneous recording of an image), the recording head portion together with the ink accommodating portion is exchanged into a new recording head portion. The recording head portion disclosed in this U.S. Pat. No. is actually removed from the printer and dumped or disposed, when the ink in the ink accommodating portion formed integrally with the recording head portion is used up, nevertheless the recording head portion can be still used if the empty ink accommodating portion is replenished with the ink. Accordingly, such recording portions have in effect been disposed wastefully.